This invention relates to the art of polysulfide and urethane polymers, processes for their preparation and cure and methods for their use.
The high molecular weight polysulfide polymers prepared in the known commercial polysulfide polymer synthesis bear hydroxyl chain terminals. When these high molecular weight polymers are chemically split to form lower molecular weight solids or liquid polysulfide polymers, the resultant macromolecules are thiol terminated. These materials, using presently available cure methods, are quite satisfactory and are commercially successful. Alternative cure methods continue to be of interest because such alternative cures hold the potential for even better properties and new uses for the novel products produced thereby. The introduction during the initial polysulfide polymer condensation of variously functionized monomers so as to produce moderate molecular weight products amenable to alternative cures has been explored previously. The introduction of unsaturation, hydroxyl, carboxyl, alkylamino, amide and aldehyde functions has been examined. The cure of the hydroxyl or unsaturation containing polymers has not proven commercially practical. The other groups are reactive with sodium polysulfide and the conditions of the initial polysulfide condensation reaction cause their loss. No direct method of splitting the initially formed, very high molecular weight polysulfide polymers to lower molecular weight products having other than thiol terminals has previously been demonstrated as practical.
Several methods of converting hydroxyl or thiol terminated polysulfide polymers to amine terminated polysulfide polymers which may then be reacted with epoxy polymers to form cured solid resins have been proposed. U.S. Pat. No. 3,322,851 illustrates the preparation of compounds of the formula EQU R'--L--(RSS).sub.x --R--L--R"
wherein L is --O-- or --S--; R' and R" are the specific alkylamino groups. ##STR1## z being selected from 0, 1, 2, 3 or 4; R.sup.iii and R.sup.iv being the same or different and being radicals selected from hydrogen, normal and branched alkyl and substituted or unsubstituted aromatic radicals; x is a positive number greater than 1; and R is an intervening polyvalent organic radical. Here the alkyl amine functionality is introduced subsequent to the polysulfide condensation reaction and any desired molecular weight adjustments.
U.S. Pat. No. 3,331,816 illustrates the preparation of alkylamino terminated polysulfide polymers of the formula: EQU (R.sup.i --L).sub.y (RSS).sub.x (R--L--R.sup.ii).sub.z
wherein L is --O-- or --S-- and wherein R.sup.i and R.sup.ii are the azomethino amino groups ##STR2## wherein R.sub.c is an alkylene group having up to 6 carbon atoms, d is an integer selected from 0, 1, 2, 3, 4 and 5; y and z are selected from 1, 2, 3 and 4; R.sub.a and R.sub.b are the same or different and are radicals chosen from the group hydrogen, normal and branched alkyl having up to 6 carbon atoms and substituted to unsubstituted alkylene-aromatic, aromatic and alicyclic radical, R is an intervening group selected from the class of intervening groups shown in U.S. Pat. No. 3,335,201, Tables I and II; and x is a positive number greater than 1. Here again, the amino terminals are introduced subsequent to the initial polysulfide synthesis and desired molecular weight adjustment.
U.S. Pat. No. 3,335,201 also illustrates amino terminated polysulfides of the structure: EQU (R.sup.i --L).sub.y (RSS).sub.x (R--L--R.sup.ii).sub.z
wherein L is --O-- or --S-- and wherein R.sup.i and R.sup.ii are the phenol amino groups: ##STR3## wherein M, N* and Q may be hydrogen, lower alkyl, and lower alkyl ether or thio ether groups, w is an integer that is one of 0, 1, 2, 3, 4, 5, and 6; y and z being one of 1, 2, 3 and 4; R.sup.iii and R.sup.iv are the same or different and are chosen from the group consisting of normal and branched alkyl radicals, alkyl ether or thio ether radicals, and substituted and unsubstituted aromatic and alicyclic radicals; x is a positive number greater than 1 and R is an intervening polyvalent organic radical. The teachings of the specification indicate that benzyl or phenyl alkylene amines are intended by including aromatic moieties among the possible identities of R.sup.iii and R.sup.iv. In this patent, also, introduction of the amine terminals is after the polysulfide condensation and any desired molecular weight adjustments. It will be noted that the structure of all the above suggested amine terminals is significantly different from those of applicant's instant invention. In addition, it is noted that all the above compositions are cured with epoxy type cures. As the above compositions are all alkyl amine terminated, they would not suggest themselves as useful curing agents in the urethane art. While alkyl amine compounds are useful catalysts in urethane cures, their high reactivity and consequent short "pot life" renders them generally not useful as urethane cure agents per se.
The reaction of liquid thiol terminated polysulfide polymers with isocyanates is well known. British Pat. No. 1,475,115 and the publication Modification of Urethane Thermo Elastomers by Polysulfide Polymers by Cherkasova et al in Sintez i Fiziko-Khimiya Polimerov, Vol. 19, pages 72-76, 1976 are recent examples. Other patents concerning mercaptan containing polyurethane compositions and curable liquid polythiopolymercaptanpolyurethane polymers are U.S. Pat. Nos. 3,446,780 and 3,440,273.
The present invention provides methods of producing aryl amine terminated polysulfide polymers in either liquid or solid form either by direct synthesis or by conversion of a previously synthesized hydroxyl terminated high molecular weight polysulfide polymer without requiring a separate molecular weight adjustment step.